是否“向后移植"Python 3 到 Python 2 的“范围"是个坏主意? [英] Is "backporting" Python 3's `range` to Python 2 a bad idea?

问题描述

我的一个课程要求使用 Python 完成作业，作为练习，我一直使用这样的脚本确保我的程序在 Python 2 和 Python 3 中都能运行:

One of my classes requires assignments to be completed in Python, and as an exercise, I've been making sure my programs work in both Python 2 and Python 3, using a script like this:

#!/bin/bash
# Run some PyUnit tests
python2 test.py
python3 test.py

我一直在做的一件事是使用这段代码使 range 在两个版本中的工作相同:

One thing I've been doing is making range work the same in both versions with this piece of code:

import sys

# Backport Python 3's range to Python 2 so that this program will run
# identically in both versions.
if sys.version_info < (3, 0):
    range = xrange

这是个坏主意吗?

这样做的原因是 xrange 和 range 在 Python 2 和 Python 3 中的工作方式不同，我希望我的代码在两者中做同样的事情.我可以反过来做，但让 Python 3 像 Python 2 一样工作似乎很愚蠢，因为 Python 3 是未来".

The reason for this is that xrange and range work differently in Python 2 and Python 3, and I want my code to do the same thing in both. I could do it the other way around, but making Python 3 work like Python 2 seems stupid, since Python 3 is "the future".

以下示例说明为什么仅使用 range 不够好:

Here's an example of why just using range isn't good enough:

for i in range(1000000000):
    do_something_with(i)

我显然没有使用列表，但在 Python 2 中，这将使用大量内存.

I'm obviously not using the list, but in Python 2, this will use an insane amount of memory.

推荐答案

您可以使用 six 包，它提供由 Python 核心开发人员之一编写的 Python 2 和 3 兼容性库.它的功能之一是重命名模块和函数的一组标准定义，包括 xrange -> range.6 的使用是官方Porting Python 2 Code to Python 3 中的众多推荐之一HOWTO 包含在 Python 文档集中.

You can use the six package which provides a Python 2 and 3 compatibility library and written by one of the Python core developers. Among its features is a set of standard definitions for renamed modules and functions, including xrange -> range. The use of six is one of many recommendations in the official Porting Python 2 Code to Python 3 HOWTO included in the Python Documentation set.

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